Fast and efficient programming + testing of devboards is essential to keeping quality high and prices low. We’ve been happy with this ‘style’ of standalone ARM Cortex tester. We use a Teensy 3.6 as the brains since it has USB host for testing the USB enumeration, and an SD card that can hold the testing and shipping firmware hex files. The programming itself uses Adafruit_DAP to perform the Cortex SWD programming procedure https://github.com/adafruit/Adafruit_DAP. a pogo pin bed allows us to quickly program and test all the IO. The only special thing on this one is due to the 0402 5.1k CC resistors – we want to verify they aren’t tombstoned so we have a little circuitry to check that the pulldowns exist by enabling a pullup and then checking the analog voltage. this setup should be about 10 seconds-per-board cycle time.
Pinout and shape is Seeed Xiao compatible, with castellated pads so you can solder it flat to a PCB. In addition to the QT connector, we also added an RGB NeoPixel (with controllable power pin to allow for ultra-low-power usage), and a reset button (great for restarting your program, or entering the bootloader)
Runs Arduino like a dream, and can be used for basic CircuitPython projects. For more advanced usage like datalogging or fire storage, solder an SOIC SPI flash chip onto the bottom pads:
Same size, form-factor, and pin-out as Seeed Xiao
ATSAMD21E18 32-bit Cortex M0+ – 48 MHz 32 bit processor with 256KB Flash and 32 KB RAM
Native USB supported by every OS – can be used in Arduino or CircuitPython as USB serial console, MIDI, Keyboard/Mouse HID, even a little disk drive for storing Python scripts.
Can be used with Arduino IDE or CircuitPython
Built in RGB NeoPixel LED
11 GPIO pins:
True analog output on one I/O pin – can be used to play 10-bit quality audio clips in Arduino (CircuitPython does not have storage for audio clips)
9 x 12-bit analog inputs (SDA/SCL do not have analog inputs)
1 x Optional AREF on A1
9 x PWM outputs (A0 is analog out, A1 is not PWM capable)
Hardware I2C port with STEMMA QT plug-n-play connector
6 x Capacitive Touch with no additional components required
3.3V regulator with 600mA peak output
Optional SOIC-8 SPI Flash chip on bottom
Reset switch for starting your project code over or entering bootloader mode
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.